Depends on the purpose of the home lab. If the primary purpose is just to act as NAS, then something like Raspberry Pi or Synology works well with very little power draw. If you want to host a plex server, which needs slightly more processing power, Intel 8th and 9th gen NUCs, with i5 processors should be more than capable. These have a power draw of about ~65 watts max, if I'm not mistaken. To this you'll have to add the power draw of externa HDDs, router (which is very little tbh), and UPS.
Mostly, if you are concerned about power consumption, then mobile processors are the way to go. They are far more efficient. Devices like Intel NUC are also very compact and a good fit for home labs.
Depending on usage, one can also consider if everything needs to keep running 24x7. For instance, I have scheduled my Synology NAS to shutdown from 1 AM to 6 AM since I never use it during that time and it can power own automatically. I also have an Amazon Plug which powers off my TV, AVR, and Raspberry Pi (which runs LibreELEC) at 12 midnight and powers it on at 8 AM. Standby power consumption for these devices are anyway pretty low, but I still prefer having them powered off at night.